1. Field of the Invention
The present invention relates to a copying apparatus having an optical scanning imaging system and more particularly to a copying apparatus having a compact erect optical imaging system.
2. Description of the Prior Art
A large number of copying apparatus are known in the prior art and are widely used commercially. Generally, these copying apparatus can vary from a simple wet process copier to complex multiple copy electrostatic copiers. The competitive pressure of a number of entrants into the copying field has increased the efforts to provide more economical machines that ate compact while at the same time maintaining the necessary requirements of image clarity. The optical systems that have been suggested and utilized in the copier field have ranged from conjugate lens systems for reproducing the entire document at one time to lenticular bars used in scanning a relatively moving original object.
One of the known problems in the copier field is the requirement of a relatively long track length between the original object and the copy. The long track length is necessary in order to provide an adequate field of view angle for the imaging objective lens system. Efforts to reduce the track length by increasing the number of lens elements correspondingly increases the cost of the lens system.
In efforts to provide a compact scanning copier apparatus, various suggestions have existed in the patent literature such as the two lenticular screens of U.S. Pat. No. 3,447,438; the pairs of lenslets suggested in U.S. Pat. No. 3,694,076; the overlapping lens strips suggested in U.S. Pat. No. 3,655,284 and the fiber optical imaging system suggested in U.S. Pat. Nos. 3,398,669 and 3,560,084.
Other strip scanning copying apparatus are suggested in U.S. Pat. Nos. 3,580,675, U.S. Pat. No. 3,836,249 and U.S. Pat. No. 3,592,542.
Attempts have been made to provide relatively inexpensive constructions of lens strip imaging devices by duplicating individual lens elements and molding them from plastic or assembling them in an array. Problems of providing the reproduction clarity required while removing vignetting, spherical aberration and field curvature problems and further maintaining a relatively economic imaging lens system has plagued these design efforts to date.
Accordingly, there is a need in the copier field to provide a compact erect optical imaging system that can be manufactured for a relatively low cost while providing minimal distortion and aberrations in the projected image.